The present invention relates to a transparent thermal insulation arrangement for the solar heating of buildings with a glass plate and an absorber arranged at a distance to the glass plate via an edge bond.
While conventional opaque building insulation in an exterior wall can only reduce heat loss from a building, transparent thermal insulation systems can utilize solar energy for the heating of buildings and provide net het gain in the course of the heating period. The term xe2x80x9ctransparent thermal insulation (xe2x89xa1 hereinafter TTI)xe2x80x9d is defined as materials which possess thermal insulation properties while they are transparent for solar radiation. Solar radiation penetrates the system and reaches the wall where it is converted into heat which is conducted through the wall into the room behind. Only a small amount of heat flows back outside. For the conversion of solar radiation into heat, it is customary to apply a radiation-absorbing layer to the wall in the form of plaster or paint.
A TTI element described by J. Geisler in the periodical xe2x80x9cSonnenenergiexe2x80x9d [xe2x80x9cSolar Energyxe2x80x9d], 4/95 (published by Verlag Solar Promotion GmbH) consists of a frame filled with drying agents into which very thinly-walled glass tubes are inserted. The glass tubes are fixed in a bond resembling insulation glass, between two highly transparent glass plates. This structure allows a large amount of the incident solar energy to pass while providing a high degree of thermal insulation against the heat stored in the exterior wall. The presence of drying agents in the insulation glass bond plus the fact that the glass tubes do not absorb any moisture means that the function of the element is not adversely affected over time through condensation in the interior of the element.
In this construction known in prior art, a gas-filled intermediate space is provided between the TTI element and the absorbent layer on the exterior wall of the building. Since gas exchange takes place between this intermediate space and the ambient air, the space is always filled with air. The intermediate space can also serve as ventilation if little or no heating effect is desired. However, condensation can form in this air space, and in particular on the absorbent layer, in case of temperature fluctuations. Dust can also settle on the absorbent layer, which over time will adversely affect the light-absorbing, solar-energy absorbing and infrared-reflecting properties of this layer. This layer must therefore be resistant to such effects. It must also be easy for contractors to apply it to several backgrounds (masonry, plaster). Normally, dark plaster or paint coats are therefore used. These have a good absorption coefficient (a to 95%), but a relatively high emission coefficient ( greater than 50%).
A transparent thermal insulation arrangement of the type mentioned above is described in DE 196 42 511 C1, from which a double-plated insulation glazing in an aluminum frame is known. In it, a black absorber film is applied to the surface facing the intermediate space between the two plates of the inner glass plate, and an insulation glazing is fastened to the exterior wall with mortar and a silicon layer, without an air space.
A disadvantage of this construction is that an additional glass plate must be provided and that this glass plate must be coated with the film-like absorber. This is time-consuming and costly. Furthermore, the application of such a TTI arrangement to an exterior wall constitutes a rather complicated and difficult process, which has the effect that once the TTI arrangement has been fastened, it cannot be removed from the wall without destroying the arrangement.
It is the object of the invention to provide a TTI arrangement which does not have the disadvantages of these prior-art system, and which in particular can be installed and dismantled in a standard work process.
This object is achieved by means of an arrangement of the above kind where the absorber consists of an inherently rigid inner absorber plate which is held together with the glass plate by an insulation-glass edge, with an intermediate space filled with an inert gas, and with an air space provided between the absorber plate and the building wall.
The arrangement according to the invention is provided with an insulation-glass edge bond between a glass plate and an interior inherently rigid or stable absorber plate. This means that the glass plate and the absorber plate are held together or bonded together by means of a spacer containing a drying agent, and that no condensation can occur in the space between the two plates. Neither can dust or other contaminants enter the inside and affect the absorber surface of the absorber plate. Since the absorbent layer is hermetically sealed and thus protected against the weather and contamination, very efficient layers can be used which, however, can also be very sensitive. The installation of the inherently rigid absorber and the glass plate is very simple and quick.
According to a preferred embodiment of the thermal insulation plate according to the invention, another glass plate is provided outside, whereby this additional plate is held together with an insulation-glass edge bond. Due to the presence of a drying agent in the outer edge bond, it is in turn ensured that no condensation can occur in the outer intermediate space either.
The intermediate space between the outer and middle glass plates can be filled with parallel layers of glass tubes, plastic honeycomb or tubular structures, but also with aerogel or other materials to suppress convection and attenuate infrared radiation, whereby preferably, an air gap is left in the intermediate space beside the honeycombs or tubes. The intermediate space between the outer and middle glass plates can also be filled with an inert gas such as krypton.